Conventionally, there is known a support device (music stand) described in the following PTL1, for example.
The conventional support device includes a fixed seat fixed to the proximity or an end or a support column and a movable seat sliding on the support column, a leg having one end pivotally attached to the fixed seat to be reversible, and a transmission rod having one end pivotally attached to the leg and the other end pivotally attached to the movable seat to be displaceable, in which at a folding completion position, a line linking a pivotally attached point between the leg and the fixed seat and a pivotally attached point between the transmission rod and the movable seat is provided to be parallel to an axis line of the support column, and the pivotally attached point between the leg and the transmission rod sandwiching the line is positioned on the opposite side of an axis line of the support column.